Note that if you are sitting old syllabus then the last chance to sit the exams is in March 2012. If you don't have the whole set by then, you may have to resit some that you have already passed. I'm not sure which ones are not credited under the new syllabus, but I understand that there are 4 or 5 in which the changes are deemed too great to credit the old for new.
That said, if you are on new syllabus, it's better to take and pass well the ones you are confident on, and defer the remainder. Just learning the answers is a bad idea and you will be found out.